What is 1990 percent of 20 - step by step solution

To get the solution, we are looking for, we need to point out what we know.

1. We assume, that the number 20 is 100% - because it's the output value of the task.
2. We assume, that x is the value we are looking for.
3. If 20 is 100%, so we can write it down as 20=100%.
4. We know, that x is 1990% of the output value, so we can write it down as x=1990%.
5. Now we have two simple equations:
1) 20=100%
2) x=1990%
where left sides of both of them have the same units, and both right sides have the same units, so we can do something like that:
20/x=100%/1990%
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for what is 1990% of 20

20/x=100/1990
(20/x)*x=(100/1990)*x       - we multiply both sides of the equation by x
20=0.050251256281407*x       - we divide both sides of the equation by (0.050251256281407) to get x
20/0.050251256281407=x
398=x
x=398

now we have:
1990% of 20=398